Authors: Yucel Birol
Publish Date: 2012/12/01
Volume: 44, Issue: 2, Pages: 359-364
Abstract
Aluminumborax powder mixtures were ball milled and heated above 873 K 600 °C to produce AlB master alloys Ballmilled powder blends reveal interpenetrating layers of deformed aluminum and borax grains that are increasingly refined with increasing milling time Thermal exposure of the ballmilled powder blends facilitates a series of thermite reactions between these layers Borax dehydrated during heating is reduced by Al and B thus generated reacts with excess Al to produce AlB2 particles dispersed across the aluminum grains starting at 873 K 600 °C AlB2 particles start to form along the interface of the aluminum and borax layers Once nucleated these particles grow readily to become hexagonalshaped crystals that traverse the aluminum grains with increasing temperatures as evidenced by the increase in the size as well as in the number of the AlB2 particles Ball milling for 1 hour suffices to achieve a thermite reaction between borax and aluminum Ball milling further does not impact the response of the powder blend to thermal exposure The nucleationreaction sites are multiplied however with increasing milling time and thus insure a higher number of smaller AlB2 particles The size of the AlB2 platelets may be adjusted with the ball milling time
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